U.S. patent number 4,101,202 [Application Number 05/749,332] was granted by the patent office on 1978-07-18 for varifocal camera objective with adjustment-range selection.
This patent grant is currently assigned to Jos. Schneider & Co. Optische Werke. Invention is credited to Karl Tesch.
United States Patent |
4,101,202 |
Tesch |
July 18, 1978 |
Varifocal camera objective with adjustment-range selection
Abstract
A varifocal camera objective, having a rotatable control ring
for adjustment to a desired focal length in a zoom range and to a
closeup position in a macro range, is provided with a pair of
independently settable stop members for selectively limiting the
adjustability to less than the entire zoom range and for optionally
excluding the macro range. The stop members coact with edges of a
stepped recess in a rim of the control ring and are each indexable
in an advanced and in a retracted position.
Inventors: |
Tesch; Karl (Bad Kreuznach,
DE) |
Assignee: |
Jos. Schneider & Co. Optische
Werke (Bad Kreuznach, DE)
|
Family
ID: |
5964177 |
Appl.
No.: |
05/749,332 |
Filed: |
December 10, 1976 |
Foreign Application Priority Data
|
|
|
|
|
Dec 12, 1975 [DE] |
|
|
2555953 |
|
Current U.S.
Class: |
359/706;
359/825 |
Current CPC
Class: |
G02B
7/105 (20130101) |
Current International
Class: |
G02B
7/105 (20060101); G02B 015/18 () |
Field of
Search: |
;350/187 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Sacher; Paul A.
Attorney, Agent or Firm: Ross; Karl F.
Claims
I claim
1. In a camera having a varifocal objective provided with control
means displaceable between a telephoto position and a wide-angle
position for adjusting the focal length of the objective in a zoom
range, said control means being further displaceable beyond said
wide-angle position for focusing the objective upon nearby objects
in a macro range, the combination therewith of:
first stop means coupled with said objective and selectively
settable to coact with said control means for blocking movement
thereof from said wide-angle position toward said telephoto
position beyond a predetermined intermediate position; and
second stop means coupled with said objective and selectively
settable independently of said first stop means to coact with said
control means for blocking movement thereof away from said
telephoto position past said wide-angle position.
2. The combination defined in claim 1 wherein said control means
comprises a manually rotatable ring centered on the objective axis,
said first and second stop means comprising a pair of axially
shiftable members engageable with abutments on said ring.
3. The combination defined in claim 2 wherein said ring has an
annular end face provided with a stepped recess with edges
constituting said abutments, said members are peripherally spaced
along said ring face within the bounds of said recess.
4. The combination defined in claim 2 wherein said members are
provided with indexing means for alternate retention in an advanced
position and in a retracted position.
Description
FIELD OF THE INVENTION
My present invention relates to a photographic or cinematographic
camera equipped with a varifocal or zoom objective and with
displaceable control means, such as a ring rotatable about the
objective axis, for selecting a desired focal length within the
zoom range as well as for focusing the camera upon a nearby object
in a so-called macro range.
BACKGROUND OF THE INVENTION
The well-known varifocal objectives have a pair of axially
shiftable components whose displacement with the aid of a camming
ring changes the overall focal length from a maximum value in a
telephoto position to a minimum value in a wide-angle position. It
is also known to design the camming mechanism in such a way that
further rotation of the ring beyond the wideangle position will
move only one of these shiftable components to displace the
previously stationary image plane so as to permit the taking of
closeups in the macro range which is usually defined as
encompassing image ratios between 1:10 and 1:1.
While it is convenient to have a single control element available
for both zooming and closeups, it is frequently desirable to
prevent an accidental overshooting of the zoom range when the
object or scene to be filmed or photographed is distant from the
camera. Furthermore, working near the telephoto end of the zoom
range generally requires a steadier support for the camera in order
to prevent objectionable blurring, making it desirable to limit the
extent of the varifocal adjustment when no tripod or the like is
available. It is also known to provide varifocal objectives with
diaphragms which automatically increase the relative aperture with
changes in the focal length, e.g. from a midposition of the zoom
range to the telephoto position. In this case, again, it may be
undesirable under certain lighting conditions to move beyond the
position where the relative aperture begins to grow larger.
It has already been proposed (see German Pat. No. 1,169,280) to
provide a zoom-type camera with a stop which arrests a camming ring
in an intermediate position unless the user makes a special effort
to deactivate that stop. This mode of operation requires a higher
degree of alertness on the part of an operator wishing to utilize
the full zoom range.
OBJECT OF THE INVENTION
It is, therefore, the object of my present invention to provide
means in such a photographic or cinematographic camera for enabling
the operator to select beforehand the extent of the range of
adjustment he wants to use, thereby allowing him to concentrate
entirely on the normal tasks of focusing and zooming without paying
special attention to the self-imposed range limitations.
SUMMARY OF THE INVENTION
I realize this object, in accordance with my present invention, by
the provision of first and second stop means selectively settable
independently of each other to coact with a camming ring or other
control means for blocking movement thereof from the wide-angle
position to the telephoto position beyond a predetermined
intermediate position and away from the telephoto position past the
wide-angle position, respectively.
BRIEF DESCRIPTION OF THE DRAWING
The above and other features of my invention will now be described
in detail with reference to the accompanying drawing, the sole
FIGURE of which shows a varifocal camera objective embodying the
present improvement .
SPECIFIC DESCRIPTION
The drawing shows, diagrammatically, a camera 20 having a rear lens
mount 3 fixedly secured thereto, this lens mount carrying a
nonillustrated fixed-focus lens group supplemented by a varifocal
front attachment of conventional type disposed within a housing.
Rotatably mounted on this housing is a focusing ring 1 with a
distance scale 1a, graduated in meters and feet, and a control ring
2 provided with a handle 4, carrying a focal-length scale 2a
graduated in millimeters. In the illustrated embodiment, the zoom
range extends from a wide-angle position with f = 6 mm to a
telephoto position with f = 70 mm. Scale 2a also indicates,
adjacent the lower limit of the zoom range, a macro range to which
the objective can be adjusted by an upward movement of knob 4
beyond the illustrated wide-angle position.
In accordance with my present invention, control ring 2 has an
annular end face proximal to lens mount 3 which is formed with a
stepped recess 6. The deepest part of this recess is bounded by
edges 9 and 10, a shallower extension 7 of the recess terminating
at an edge 11. On its opposite side the recess 6 has a still
shallower extension 5 bounded by an edge 8.
Two stop members 13 and 15 in the form of axially extending pins
are lodged in lens mount 3 and are provided with actuating knobs 12
and 14 received in slots of that lens mount in order to facilitate
a shifting of these pins between an advanced position at left and a
retracted position at right. The pins can be indexed in either of
their positions by respective spring-loaded ball checks 18 and 19
engaging in notches 16 of pin 13 and notches 17 of pin 15. With pin
13 in its advanced position, as illustrated in full lines, the zoom
range is curtailed to end in the 40-mm position in which the pin
comes to rest against edge 10 as indicated in phantom lines at 13'.
With pin 15 advanced, as also shown in full lines, the upward
movement of handle 4 is stopped in the wide-angle position in which
this pin abuts the edge 9. Retraction of pin 13 opens up the full
zoom range from 6 to 70 mm, the pin engaging the edge 11 in the
telephoto position as indicated in phantom line at 13". The macro
range is available upon retraction of pin 15 which then engages the
edge 8 as indicated in phantom lines at 15'. Recess edges 8 and 11
could also be replaced by lugs projecting from ring 2 toward lens
mount 3.
Obviously, the peripheral separation of pins 13 and 15 along the
recessed end face of ring 2 must be at least equal to the angular
extent of the macro range if the end of that range is to be
determined in the aforedescribed manner by the coaction of pin 15
with edge 8. With edge 9 higher than edge 10, however, the macro
range could also be limited by contact between edge 9 and pin 13 in
either its advanced or its retracted position. In either case, the
two stop pins 13 and 15 allow a preliminary selection to be made
among four different working modes, namely:
(a) full zoom plus macro range,
(b) curtailed zoom plus macro range,
(c) full zoom without macro range,
(d) curtailed zoom without macro range.
With the objective focused on the macro range, the advance of pin
15 is prevented by the bottom of recess extension 5. Similarly, pin
13 cannot be advanced in the upper part of the zoom range in which
it confronts recess extension 7.
While the embodiment described above is designed for manual
adjustment of ring 2, it will be apparent that the same range
limitations can be selectively imposed if the ring is electrically
driven by a reversible motor through the intermediary of a friction
clutch, e.g. as described in commonly owned U.S. Pat. Nos.
3,165,044, 3,656,422 and 3,682,072.
* * * * *